A. Field of Invention
This invention pertains to an apparatus for analyzing railroad car wheels to detect certain conditions which may result in a derailment, and more particularly to a system which performs the analysis after data has been collected from a moving car.
B. Description of the Prior Art
Derailments on railroads cause major problems because they may result in injuries, loss of life and they are also very expensive and cause extreme time delay. Since derailments are caused very often by either hot wheels or hot wheel bearings, extensive wheel monitoring systems have been installed for monitoring the wheel temperatures. These temperatures are then compared to certain threshold levels and if the temperature of a wheel (or bearing) exceeds a threshold, an abnormal condition is established. The level of the threshold is critical to the operation of the railroad. If this level is too high, an overheated wheel or bearing may not be detected until a derailment occurs. If the level is set too low, a false alarm may be generated. False alarms resulting in a stopped train are more tolerable then derailments because they normally do not result in loss of life or property, however they still cause delays, complications in train schedules and consequently are very expensive.
Some systems are known in which the temperature thresholds are not fixed but are adjusted dynamically between an absolute minimum and an absolute maximum level. For example the temperatures of all the wheels of a car, or train, could be averaged and then the threshold can be calculated using this average. However, this procedure requires the capability of identifying, differentiating and associating the wheels to a car. In the prior art systems, if a wheel is not identified as being associated with a particular car, then the absolute threshold level is used for the comparison. However, this solution is unsatisfactory because it may lead either to derailments due to missed hot bearings or false alarms and the absolute alarm thresholds cannot be modified to make effective use of alarm criteria based on car average temperatures.